Renal System Flashcards

1
Q

process of evolution in kidneys

A
  1. auqatic organisms used cellular transport to miaintain differences between ECF and seawater
  2. development of out epithelial layer to restrict water flow into body
  3. terrestrial environment = diversifying limits to water loss
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2
Q

vertebrate renal evolution

A
  1. pronephros = single giant nephron does filtration for body, simple blood vessels and cilia on tubules for filtration, k=kidney directly connected to veins, single nephron
  2. mesonephros = bowmans capsules formed at end of tubules (c shaped cups capsules), 24-100 nephrons, glomeruli present
  3. Metanephric = ureter emergence, clusers of many smaller nephrons (millions)
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3
Q

loop of henle

A
  • used to concentrate urne
  • ascending loop not formed a birth
  • ascending and descending limbs
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4
Q

features and functions of kidneys

A
  • villi = increase SA for transport
  • mitochondria abundance = energy for active transport
  • tight junctions = block passage of solutes between cells -> barrier = control
  • transporters = allow movement/transport
  • renal tubules are lined with epithelial cells -> used paracellular and transcellular transport
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5
Q

What is transcellular transport

A
  • need proteins on both sides of membrane/cell to move solutes through
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6
Q

what is paracellular transport

A
  • solute moves through junctions between cells
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7
Q

process occuring in kidneys

A
  1. filtrattion -> movement of solutes/solvent from blood into kidney (bulk movement from glomerullar capillaries to neohron)
  2. reabsorption -> movement from filtrate to peritubular capillaries (back into renal vein and blood)
  3. secretion -> movement of specific solutes from peritubular capillaries back into filtrate
  4. Excretion -> loss of filtrate as urine intto bladder via ureters
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8
Q

explain the structure of glomerulus

A
  • coarse seive
  • capillaries are very leaky between cells (only protein and blood filtered)
  • epithelial cells = podocytes
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9
Q

what is GFR

A
  • glomerular filtration rate
  • volume of fluid filtered by both kidneys per unit of time
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10
Q

What factors determine GFR

A
  1. permeability of filtration barrier
  2. SA for filtration
  3. glomerular filtration pressure (only one to change short term)
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11
Q

What two pressure gradients determine filtration across the glomerulus

A
  1. hyrdostatic pressure (exerted by fluid inside pressure on walls)
  2. oncotic pressure (exerted by water moving down conc gradient)
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12
Q

what are the pressure gradient differences across the glomerular capillary and bowman’s capsule?

A
  1. hydrostatic pressure higher in glomerulus than bowman’s
  2. osmotic pressure higher in glomerular capillary due to proteins (no protein in bowman’s capsule)
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13
Q

how does capillary hydrostatic pressure influence GFR

A
  • mean arterial pressure (increased = increased glomerular pressure = increased filtration)
  • afferent resistance -> increased resistance = decreased glomerular pressure = lower filtration)
  • efferent resistance = high glomerular pressure = higher filtration
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14
Q

what occurs in the proximal tubule?

A
  • bulk reabsorption of nutrients
  • unregulated absorption
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15
Q

features of proximal tubule for absorption

A
  • surrounded by dense capillary network
  • winding structure (convoluted)
  • extensive microvilli,
  • high numbers of mito,
  • “leaky” tight junctions (lots of stuff leaving tubule between cells),
  • many and diverse transporters
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16
Q

What occurs in the descending limb of henle

A
  • passive water reabsorption
  • permeable to water, not salt/ solutes
  • water moves down electrochemical gradient through aquaporins in descending Limb all the time (always there)
17
Q

How does ECF concentration determine conc of urine in descending loop

A
  • fluid can only have osmolarity same as ECF because will only flow when there is a concenntration gradient
  • must be a difference for water to flow, so once it reaches isotonic level will stop
  • further down loop, more concentrated
18
Q

What occurs in ascending loop of henle?

A
  • active solute reabsorption
  • impermeable to water and salt is actively transported
  • decreasing concentration on ascension -> removing salt
  • transporters moving Na+ and Cl- across into blood, dependent on K+ cycling on both apical and basolateral membranes because sets up conc gradients
19
Q

What occurs in the Collecting duct?

A
  • regulated water reabsorption
  • use of hormones to control transport
  • fine tuning of composition of urine in distal tubule
20
Q

Effects of ADH (antidiuretic hormone

A
  • opposes production of urine (decrease vol), will increase reabsorption of water into blood to reduce filtrate
    -passive movement of water turned on and off by hormones moving aquaporins
21
Q

steps of ADH movement of aquaporins

A
  1. ADH acts on basolateral membrane receptors
  2. triggers exocytosis of aquaporin storage vesicles inside membrane cells of collecting duct
  3. increases aquaporins in luminal membrane
  4. increases water reabsorption
22
Q

How is concentration of urine changing dwn collecting duct if no ADH present?

A
  • it cannot change because water can’t move across the apical/lumen membrane